Estimated nephron number of the remaining donor kidney: impact on living kidney donor outcomes.

BACKGROUND

It has been demonstrated that low birth weight gives rise to a reduction in nephron number with increased risks for hypertension and renal disease. Its impact on renal function in kidney donors, however, has not been addressed.

METHODS

To investigate the impact of birth weight, kidney weight, kidney volume and estimated nephron number on kidney function, we collected data from 91 living kidney donors before nephrectomy, at +12, +36 and +60 months after nephrectomy.

RESULTS

Birth weight showed a positive correlation with estimated glomerular filtration rate (eGFR) at +12, +36 and +60 months after nephrectomy (P < 0.05). The strongest link was observed in donors >50 years old (R = 0.535, P < 0.001 at +12 months). Estimated nephron number and eGFR showed a strong positive correlation at +12, +36 and +60 months after nephrectomy (R = 0.540; R = 0.459; R = 0.506, P < 0.05). Daily proteinuria at +12 months showed a negative correlation with birth weight (P = 0.009). Donors with new-onset hypertension showed significantly lower birth weights and higher uric acid levels (P < 0.05). Kidney weight and volume did not show any impact on donor outcomes (P > 0.05).

CONCLUSIONS

Low nephron number predisposes donors to inferior remaining eGFR, hypertension and proteinuria. The strong correlation in elderly donors may be attributed to reduced renal functional reserve due to the decline of renal function with age.